The invention pertains to an integrated comparator circuit employing insulated-gate field-effect transistors of the same conductivity type. More specifically, the invention pertains to a comparator circuit which in response to an arbitrary potential difference at two inputs generates an output signal with either a low-level state possibly corresponding to the potential of the zero point of the circuit, or a high-level state possibly corresponding to the potential of the source of operating voltage.
Such comparator circuits can be used, for example, as sense amplifiers for memories employing static memory cells operating e.g., on the flip-flop principle. The potential difference occurring at the two outputs of such memory cells is equal to the voltage difference between the high-level state at the one output and the low-level state at the other output, and vice versa. This difference is to be "read" or in such a way that the maximum difference between the high-level state and the low-level state will occur at this output, i.e., that the two states are each as close as possible to the potential of either the zero point of the circuit or that of the operating voltage. Moreover, the circuit is required to respond safely to small potential differences at the input, i.e., the sensitivity of the circuit within the area of the potential difference zero at the input is supposed to be as great as possible, thus noticeably increasing the response rate.
It is desireable for such a comparator circuit to have a low current consumption. It is further desireable that a comparator circuit used as part of an overall integrated circuit, for example, as part of a memory matrix, be as insensitive as possible with respect to manufacturing process parameter fluctuations. It is also desireable that an integrated comparator circuit use little surface area.